Dino Crisis kodai:

Alternate costumes:
Successfully complete the game to unlock the
Army and Battle costumes for Regina. Successfully
complete the game a second time to unlock the
Ancient (caveman) costume.

Grenade gun:
Successfully complete the game three times.
The grenade gun with unlimited ammunition will
be available at the start of the next game.

Operation: Wipe Out mode:
Successfully complete the game with a time under 5:00:00.

Puzzle preview:

When at a puzzle, before changing it, around push
the button. Nothing will happen, but if you watch
the colored lights they will turn on in the order
needed to solve the puzzle.

Shutters:

Since the dinos can not pass through a shutter, use
them to your advantage. Close each shutter after you
pass them. This way, if a dino appears in that particular
area, you can not be attacked (unless, of course, you
are on the same side as the dino).

Save ammo:

There are some areas that you will only pass
through once or twice in the entire game.
Killing the dinos in these areas is pointless;
more importantly, it is a waste of ammo.
Use the weakest tranquilizer dart on it/them,
and move on. This way, the bullets/shells/slugs/grenades
are available when you need them. Once you get unlimited
grenades (by completing the game three times under the
normal difficulty setting),
you can kill those dinos, without wasting ammo.

Get the third Energy Key Card early:

Before leaving the jungle, you can retrieve the card from
the shallow stream. This way you will not have to make a
return trip after finding out that it is needed.

View Ending 3 without agreeing with Rick:

It is possible to get Ending 3 after agreeing with Gail.
When the game prompts you to agree with Rick or Gail at
the end of the game, choose Gail's decision to go after
Dr Kirk. After the intermission sequence, go out the main
door of the room. Go across the room to the double doors
that lead to the Central Stairway. Once in the Central
Stairway, if you have the infinite grenade gun, kill the
two dinos in the room. If you are low on ammo and do not
have the infinite grenade gun, try to run around them and
not get hit. Go all the way to the end of the hallway to
the Security Level A door. Go through that door, which leads
to the Port Transport Passageway. Get on the slider and go
across to the other side. When you get there, get off of the
slider and go through the large sliding door to the Heliport
Transport Passageway. Get onto the new slider and go across
to the other side of this area. When you arrive, you should
see a large door in the middle of the wall in front of you
and a small Security Level A door to the right of it. That
door leads to the Underground Heliport. Enter the Underground
Heliport through the Security Level A door as the Large one
will not open. Walk forward until you see a sequence that shows
the helicopter. When you regain control of Regina, exit the
Underground Heliport. Go back across the slider closest to the
Underground Heliport. When you arrive back at the other side,
do not go through the large sliding door to your right.
Go through the large door in front of you. The room you enter
is the Transport Passageway, not the Port Transport Passageway.
Be careful, as a dino will attack you. Kill the dino, then walk
forward until you reach the Security Level A door that is on the
right of the screen. Enter through that door, which leads to the
Special Weapons Storage. You will find Gail and Dr.Kirk.
The intermission sequence will take you back to the Underground
Heliport. When it completes, go back out the door to the Heliport
Transport Passageway. After that intermission sequence, kill the
T-Rex. When he is defeated, Ending 3 will play and you have
successfully viewed it without agreeing with Rick.

Hint:

Several times throughout the game, you'll be challenged
with DDK codes you will have to enter in order to gain
access to certain rooms. Each puzzle starts with a jumble
of letters on top and a code key on the bottom. Use the
code key to eliminate the corresponding letters up top
and form the password.

At times, shortcuts can be found throughout the building
in the form of air ducts. If you see an open air duct
anywhere, use it to cut corners to new areas and avoid
tough enemies.

Read every document you come across. Just about every
piece of readable paper contains some sort of passkey,
tip for mixing medical supplies, or insight into what
really happened on the island.